American planetary astronomer Mike Brown (and fellow astronomers at California Institute of Technology in Pasadena) and J.L. Ortiz (and colleagues from Instituto de Astrofisica de Andalucia at Sierra Nevada Observatory, Spain) discovered 2003 EL61, also called (136108) 2003 EL61, about two years ago.

From their studies, the Caltech scientists think that the object got its odd movements and shape from a collision between two objects about 4.5 million years ago. It is made mostly of rock, when many objects nearby are made of ice. They surmise that the collision knocked all the ice off the rocky core and made it spin in an awkward way, which caused its football-like shape.

During these past two years, the astronomers only had this one object to study. However, they just found another five objects that look surprisingly similar to 2003 EL61. These five objects were found beyond the orbit of Neptune at about 2.8 to 4.6 billion miles from the Sun.

These objects are unusual because collisions of asteroids have never been found in this region of the solar system. Collisions are very common within the asteroid belt in the inner solar system, but such a collision has never been found to occur in the outer solar system beyond Neptune, a region of space usually reserved for what are called trans-Neptunian objects (TNOs).

Trans-Neptunian objects are made up of three distinct groups: the Kuiper belt (Kuiper belt objects [KBOs] such as the dwarf planets Pluto and Eris), the Scattered disk (icy minor planets called scattered disc objects [SDOs]), and the Oort cloud (a mass of comets).

Brown and his collaborators do not think this object is very stable. In fact, they think that some smaller fragments from the collision have already traveled into the inner solar system and may have even hit the Earth. If so, Brown thinks 2003 EL61 may eventually wind up as a comet and be seen streaking past the Earth. If this happens it would be as bright as a full Moon and one of the most dramatic comets ever to be seen from the Earth.

But, don’t get your hopes up too much. This trip to the Earth by 2003 EL61 would not occur, according to Brown,  for a billion years or so.

The result of their research is reported in the journal Nature.

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Astronomy  Research  Science  Solar system  Space  Sun  William Atkins